In a solar cell industry, solar cells are classified into a first generation solar cell, a second generation solar cell, and a third generation solar cell, in consideration of manufacturing cost and efficiency. The first generation solar cell is a crystalline silicon solar cell which has been developed over the last several decades, and currently, the crystalline silicon solar cell accounts for more than 80% of the entire solar cell. The second generation solar cell, which is a solar cell for compensating for disadvantages of a silicon solar cell having relatively high efficiency but expensive manufacturing cost, means a thin film solar cell made of amorphous silicon, a compound and an organic thin film, and the like. In addition, the third generation solar cell, which is a solar cell for obtaining high efficiency at low cost, is a new conceptual solar cell utilizing a nano structure and a quantum-dot (QD).
Since the silicon solar cell, which is the first generation solar cell, has already reached a technical limit, currently, research into and development of the second generation thin film solar cell has been mainly and actively conducted. However, in order to rapidly reach grid parity of the solar cell, development of a low-cost and high-efficiency third generation solar cell has been demanded.
As a general technology for forming a silicon quantum-dot, which is a core of the third generation solar cell, according to the related art, there is a method of forming the quantum-dot by adding a larger amount of silicon than an amount of silicon required to form SiO2 having an accurate composition at the time of depositing a silicon dioxide film (SiO2) to allow the larger amount of silicon to be precipitated during a thermal treatment process.
However, in the method according to the related art, there is advantage in that it is possible to form quantum-dots at distances relatively equal to each other from a channel in which a current flows while obtaining a sufficient throughput during a process of forming the quantum-dots, but there are disadvantages in that the distances are relatively long, such that a density of the quantum-dot is slightly low, and sizes and spatial distribution of the quantum-dots are not uniform.
Therefore, there is a need to develop a quantum-dot photoactive-layer in which a density of the quantum-dot is increased and sizes and spatial distribution of the quantum-dots are uniform.
As the related art associated to a method of manufacturing a quantum-dot, there is Korean Patent Laid-Open Publication No. 10-2012-0058840.